1. Field of the Invention
The invention pertains generally to computers. In particular, it pertains to management of the BIOS image in computers.
2. Description of the Related Art
Computers are usually initialized by executing a Basic Input/Output System (BIOS). The BIOS is non-volatile code that determines what the computer can do without accessing programs from a disk. On personal computers (PCs), the BIOS contains all the code required to perform a self-test and to control the keyboard, display screen, disk drives, serial communications, and a number of miscellaneous functions. The BIOS then loads the operating system from disk. Originally, the BIOS was placed in a read-only memory (ROM) and could not be modified without physically replacing the ROM. As the functions performed by the BIOS became more complex, and computers became easier to reconfigure after manufacture, the BIOS was placed on rewritable programmable ROMs, such as flash memory.
Since the BIOS can now be rewritten in the field after the computer becomes operational, and a computer cannot be booted without a valid BIOS, this raises reliability and security issues. A computer can be disabled if the BIOS is corrupted by being rewritten incorrectly, such as by user error, power interruption, or software malfunction. To help prevent an unrecoverable condition, many systems contain a backup copy of the system BIOS that can be relied upon if the primary BIOS is faulty. However, these generally require physical intervention by the user to activate the backup BIOS. For example, the backup BIOS may be enabled by a mechanical switch or jumper on the motherboard. Those systems that have some sort of automatic recovery still require the physical presence and intervention of an operatorxe2x80x94to choose boot options or to insert a recovery disk, for example. If the faulty BIOS was caused by a download to a remote system with no operator present, the corrective action (dispatching a technician to the site) can be very expensive in terms of both money and downtime. An additional disadvantage of the convention BIOS redundancy approach is that the two BIOS copies are usually stored in two separate memory devices, which increases manufacturing costs.